CONFIG_MACH_SFFSDR is not available for the selected architecture x86.
Result is shown for architecture arm

Lyrtech SFFSDR

modulename: board-sffsdr.ko

configname: CONFIG_MACH_SFFSDR

Linux Kernel Configuration
└─>TI DaVinci Implementations
└─>Lyrtech SFFSDR
In linux kernel since version 2.6.31 (release Date: 2009-09-09)
Say Y here to select the Lyrtech Small Form Factor
Software Defined Radio (SFFSDR) board.
source code:
arch/arm/mach-davinci/board-sffsdr.c